Conversion of hydrocarbon oils



A ril 8, 1-941. 1.. c. HUFF CONVERSION OF HYDROCARBON OILS Filed March21. 1938 INVENTOR LYMAN C. HUFF ATTORNEY mwzuuum on ZuQZOU HN I I Y m:mU ZmDm m: ON

Patented Apr. s, 1941 CONVERSION OF HYDROCARBON OILS Lyman C. Hufi,Chicago, Ill., assignor to Universal Oil Products Company, Chicago,111., a corporation of Delaware Application March 21, 1938, Serial No.197,090

6 Claims.

This is, in part, a continuation of my co-pending application SerialNumber 98,669, filed August 31, 1936, which, in turn, is acontinuationin-part of my now abandoned application Serial Number 6,987,filed February 18, 1935.

My previous applications, above referred to, disclose a crackingoperation of the type wherein relatively light and relatively heavyhydrocarbon oils are cracked under independently controlled conversionconditions, with provision for absorbing desirable high-boilingcomponents of normally gaseous conversion products of the process in asuitable relatively light absorber oil and supplying the resultingenriched absorber oil to the light oil cracking step of the system. Thepresent process embodies a similar type of operation which includes theadditional cooperative features of topping crude petroleum chargingstock for the system by intimate contactwith hot vaporous productsresulting from the flash distillation of residual liquid conversionproducts of the process, said topping being effected in a fractionatingstep of the hash distilling system wherefrom light distillate, includinggasoline components of the crude, is recovered and utilized as at leasta portion of the absorber oil, the resulting enriched absorber oil beingreturned, as in the process of the previous applications, to the lightoil cracking step of the system whereto other low-boiling intermediateliquid conversion products of the process are also supplied for crackingtreatment.

The above described and other features of the process will be apparentfrom the accompanying diagrammatic drawing and the following descriptionthereof. The drawing illustrates one specific form of apparatusembodying the features of the invention and in which the process of theinvention may be conducted.

Referring to the drawing, heating coil l to which relatively heavyhydrocarbon oil is supplied, in the manner later described, forcracking, is located within a furnace 2', by means of which heat issupplied to the oil passing through the heating coil to bring it to thedesired crackresidual liquid conversion products in this zone and arewithdrawn from the upper portion of the chamber and supplied throughline 6 and valve 1 to fractionator 8.

Fractionator 8 is preferably also maintained at a substantialsuperatmospheric pressure, which may be substantially the same orsomewhat lower than that employed in reaction chamber 5. Thefractionator may employ any desired type of fractionating means such as,for example, perforated pans, bubble trays, packing or the like, wherebythe vaporous conversion products supplied from reaction chamber to thiszone are fractionated for the separation therefrom of high-boilingcomponents which are condensed as reflux condensate. Reflux condensateformed in fractionator 8, high-boiling fraci-ZO ing temperature,preferably at a substantial sutions of the heavy oil charging stock, andother heavy oils, which are supplied to this zone as will be laterdescribed, are directed from the lower portion of the fractionatorthrough line 9 and valve It] to hot oil pump II by means of which theyare fed through line [2 and valve l3 to heating coil I for conversiontherein as previously described.

Fractionated vapors of the desired end boiling point, which remainuncondensed in fractionator fl, are directed from the upper portionthereof through line l4 and valve iii to fractionator l6. FractionatorIt is preferably operated at a low superatmospheric pressure, relativeto that employed in fractionator 9, and may employ any desired type offractionating means such as, for example, perforated pans, bubble trays,packing or the like, whereby the vaporous conversion products suppliedfrom fractionator 8 to this zone are separated into reflux condensate,comprising their high-boiling components and a fractionated vaporousstream preferably having an end-boiling point within the range ofgasoline. To assist in the proper rectification of the reflux condensateformed in fractionator iii, a suitable vaporizing or heating medium,such as steam, heated hydrocarbon vapors or gases, etc., may beintroduced into the fractionator through line I1 and valve I8 below thelevel of reflux condensate maintained in this zone. When desired, anyother suitable method of reboiling the reflux condensate may beemployed, such as, for example, indirect heat exchange with relativelyhot vapor or liquid from Within the system or from an external source.

Fractionated vapors and gases, which remain uncondensated infractionator it, are directed from the upper portion thereof throughline Ill and valve 29 to cooling and cOndensation in condenser 21, theresulting distillate and uncondensed gases passing through line 22 andvalve 23 to collection and separation in receiver 24.

The residual liquid conversion products remaining unvaporized inreaction chamber are removed from the lower portion of this zone throughline 25 and valve 26 and may be directed, all or in part, to storage orany desired liquid conversion products supplied to this zone isaccomplished. When desired, any suitable fractionating means may beemployed in the upper portion of this chamber 3! to assist theseparation of mist and entrained heavy liquid particles from the vapors.conversion products remaining unvaporized in chamber 3i are withdrawntherefrom through line 32 and valve 33 to pump 34 by means of which theymay be supplied through line 55 and valve 35 to storage or elsewhere asdesired. When 3- desired, the residual liquid remaining unvaporized inchamber 3| may be reduced to substantially dry coke therein or externalthereto, by any well known means, not illustrated.

Vapors evolved in chamber 3| are withdrawn 1 from the upper portionthereof through 1ine'3l The residual liquid and valve 38 and aresupplied to fractionator 39,

wherein they may be directly commingled with hydrocarbon oil chargingstock supplied to this zone and wherein the commingled materials arefractionated for the formation of reflux condensate, comprising theirhigh-boiling components. Any desired type of fractionating means may beemployed in this zone, such as, for exam ple, perforated pans, bubbletrays, packing or the like.

Charging stock supplied through line 49 and valve 4| to pump 42 maycomprise any desired type of hydrocarbon oil but preferably is an oil ofrelatively wide boiling range, such as crude petroleum, topped crude orthe like.

When the charging stock contain a substantial quantity of low-boilingcomponents, such as poor antiknock gasoline or gasoline fractions, it ispreferably supplied from pump 42 through line 43 and valve 44 intofractionator 39. In this zone the charging stock intimately contacts andcommingles with the vaporous products supplied thereto from chamber 3!.The charging stock is thus at least partially vaporized and thecommingled vapors are fractionated in this zone. The reflux condensateformed in fractionator 39 and any unvaporized, high-boiling fractions ofthe charging stock supplied thereto are withdrawn in a commingled statefrom the lower portion of this zone through line 45 and valve 46 to pump41 by means of which they may be supplied through line 43, valve 49 andline 59 to fractionator 8, to commingle therein and undergo sired, frompump 42 through line 53 and valve 54 into line 48 and thence tofractionator 8.

The fractionated vapors which remain uncondensed in fractionator 39 aredirected from the upper portion of this zone through line 55 and valve56 to cooling and condensation in condenser 51. The resulting distillateand uncondensed gases pass through line 58 and valve 59 to collectionand separation in receiver 69.

A regulated portion of the distillate collected in receiver 24 may berecirculated through line iii, valve 62, pump 63, line 64, line andvalve 55 to the upper portion of fractionator I6, and/ or through line61 and valve 68 to the upper por- 3 tion of fractionator B to serve as acooling and refluxing medium in one or both of these zones. That portionof the distillate collected in receiver 24- which is not required as acooling and refluxing medium may be withdrawn to storage or any desiredfurther treatment, by well known means, not illustrated. Preferably,however, the distillate is first subjected to stabilization for thepurpose of liberating therefrom regulated quantities of dissolvednormally gaseous products, whereby to reduce its vapor pressure to thedesired degree. To accomplish this, distillate is directed from receiver24 through line 69 and valve itlto pump 11' and thence through line 12and valve T3 to heat exchanger 14, wherein it is heated, by indirectheat exchange with the final stabilized product ofthe process, as willlater be more fully described; sufficiently to cheat its substantialvaporization in stabilizer Tl'to which it is directed through line 15and valve I6;

Stabilizer Tl may be any conventional type of stabilizing equipmentemploying suitable fractionating means and capable of effectingrectification of the distillate to the desired vapor pressure. In thecase here illustrated, unvaporized distillate is withdrawn from thelower portion of stabilizer 1'! through line l8 and valve 19 to reboiler89 wherein it is maintained at a substantially constant temperature,sufiicient to reboil the same, by means of its indirect heat exchange inthe reboiler with any suitable heating medium which, in the case hereillustrated, comprises a regulated portion of the reflux condensatewithdrawn from fractionator 8 and supplied to the reboiler as will belater described. The vapors and/or gases evolved in reboiler 89 arereturned therefrom through line 18' and valve 19 to stabilizer H. Thestabilized and reboiler distillate is withdrawn from reboiler 89 throughline 8| and valve 82 to heat exchanger 14, wherein it is passed inindirect heat exchange with and supplies heat to the unstabilizeddistillate passing from receiver 24 to stabilizer 11, as previouslymentioned, and is removed through line 83 and valve 84 to furthercooling and storage or to any desired further treatment, notillustrated.

In the case here illustrated, a regulated portion of the refluxcondensate withdrawn from fractionator 3 is utilized as a heating mediumin reboiler 89; to assist vaporization of thematerial undergoingstabilization in stabilizer i7, and may be directed from the lowerportion of fractionator 8 through line 9 and thence through. line 85 andvalve 86 to pump 81 by means of which it is supplied through line 89 andvalve 89 into reboiler 89, through which it passes in indirect heat exchange with the distillate from stabilizer 11. It is also within thescope of the invention to utilize regulated quantities. of thecommingled heavy oils withdrawn. from thelower portion of fractionator39 as a heating medium in reboiler To accomplish this regulatedquantities of this material are diverted from line 50 through line soand valve 9| into line 85 leading to pump 8'! and reboiler 80. Thepartially cooled heating medium having passed through reboiler 80 isdirected therefrom through line 92 and may be .supplied, all or in part,to fractionator 8 by means of line 94, valve95 and line 50, or it may besupplied, all or in part, through line 96 and valve 91 into line Ii, tocommingle with and partially cool the vaporous conversion productspassing from reaction chamber 5 to fractionator 8.

Gaseous products separated from the distillate in receiver 24 may bedirected therefrom to storage or elsewhere as desired, by well knownmeans not shown, but preferably are supplied through line 98 and valve99 to absorber I00. Normally gaseous products liberated from thedistillate in stabilizer H and released from the upper portion of thiszone through line IIJI and valve I02 are supplied through line 98 toabsorber I00, either alone or together with gases previously separatedfrom the unstabilized distillate in receiver 24. The gaseous productsreleased in receiver 6b through line I03 and valve I04 may also besupplied to absorber I00, by well known means not shown, or they may bewithdrawn from the system to storage or elsewhere, as desired.

The normally gaseous products supplied to absorber Illll are passed indirect counter-current contact with a suitable absorber oil, whichserves to absorb desired high-boiling components of the gases,consisting principally of gases having 3 and more carbon atoms to themolecule. The lower boiling, unabsorbed gases are released from theupper portion of the absorber through line it'll and valve I02.

When desired a selected absorber oil from an external source may besupplied to absorber I08 through line I85 and valve I06. Preferably,however, the low-boiling oil recovered as the overhead distillateproduct from fractionator 39 is utilized, either alone or in conjunctionwith other low-boiling oils, as the absorption medium in absorber IM.Distillate may be directed from receiver 6!! through line I01 and valveI08 to pump Hill by means of which it may be supplied through line H andvalve III to the upper portion of absorber not. Light reflux condensatefrom fractionator It may also be employed as absorber oil,

when desired, regulated quantities of this material being directed fromfractionator I6 through line I2I and valve I22 to pump I23 and thencethrough line I24, valve I25 and, line IIII into absorber Illll.Preferably when light reflux condensate from fractionator I6 is thusutilized it is cooled, by Well known means not shown, prior to itsintroduction into absorber I00.

The enriched absorber oil is withdrawn from the lower portion ofabsorber I00 through line I I2 and valve I I3 to pump I I4 by means ofwhich it is supplied through line H and valve IIG for conversion inheating coil III. Light reflux condensate from fractionator I6, or thatportion thereof not supplied to absorber I00, is directed from line I24through line I24 and valve I25? into line H5 and thence to furthercracking in heating coil II'I,

Coil H1 is disposed in a furnace IIB, of suitable form, by means ofwhich heat is supplied to the relatively low-boiling oils and normallygaseous products passing through the heating coil to bring the same tothe desired cracking temperature,preferably at a substantialsuperatmospheric pressure. Although illustrated conventionally in thedrawing, coil Ill and furnace II8 preferably comprise one of the wellknown types of heaters wherein the materials passing through this zone,after being heated therein to the desired cracking temperature, aremaintained in a final soaking section of the heating coil for apredetermined time at a substantially constant temperature relativelyclose to the maximum temperature previously attained in the coil,whereby conversion of the oils and gases into high yields of goodantiknock gasoline is accomplished,

Preferably, the material undergoing conversion in heating coil III issubjected therein to more severe cracking conditions than those employedin coil I. The conditions of temperature, pressure and time employed inthis zone are preferably within the range of the so-called reformingconditions, whereby the antiknock qualities of the gasoline or gasolinefractions supplied to coil II! are materially improved withoutexcessively altering their boiling range. Such conditions are alsomaintained within the range suitable for converting any higher boilingoils supplied to coil I H, as well as the olefinic gases supplied to andformed in this zone, into substantial yields of liquid products boilingwithin the range of gasoline and of good antiknock value. The stream ofheated products discharged from heating coil II! are supplied throughline H9 and valve I20 into reaction chamber 5,, wherein these relativelyhot products commingle with the less highly heated products supplied tothis zone from heating coil I and wherein the commingled materials aresubjected to continued conversion at their attained temperature.

The preferred range of operating conditions which may be employed, in anapparatus such as is illustrated and above described, to produce thedesired results, are approximately as follows: Heating coil I may employan outlet conversion temperature ranging, for example, from 825 F. to950 F., preferably with a superatmospheric pressure at this point in thesystem of from to 500 pounds, or thereabouts, per square inch. Reactionchamber 5 may utilize the same or somewhat lower pressure than thatemployed in heating coil I, and substantially the same or somewhat lowerpressure may be utilized in fractionator 8.

Fractionator I6 is preferably operated at a substantially reducedpressure relative to that employed in the preceding portion of thesystem and this reduced pressure may range, for example, fromsubstantially atmospheric to pounds, or more, per square inch,superatmospherlc pressure. Substantially the same or somewhat lowerpressure may be employed in the succeeding condensing and collectingequipment.

Flash chamber 3| is preferably operated at a substantially reducedpressure relative to that employed in reaction chamber 5 and thisreduced pressure may range, for example, from substantially atmosphericto 150 pounds, or thereabouts, per square inch, superatmosphericpressure. Fractionator 39 and the succeeding condensing, and collectingportions of the system may employ substantially the same or somewhatlower pressure than that utilized in chamber 3|.

The conversion temperature employed at the outlet of coil II! willdepend upon the composition of the materials supplied to this zone, andmay range from 900 F. to 1200 F. with a superatmospheric pressure atthis point in the 'fractionator 39 from chamber 3|.

system ranging, for example, from 300 to 1200 pounds, or thereabouts,per square inch. The pressure employed in the stabilizing zone mayrange, for example, from 100 to 300 pounds, or thereabouts, per squareinch. Any desired pressure within substantially the same range may beutilized in the absorption zone,

As an example of one specific operation which may be conducted inaccordance with the features of the invention and in an apparatus suchas illustrated and above described: The charging stock is a Montana CutBank crude oil of approximately 34.'7 A. P. I. gravity having an initialboiling point of approximately 160 F. and containing approximately 35%of materials boiling up to 400 F. The straight run gasoline which is ofpoor antiknock value, is separated from heavier components of the crudein fractionator 39 and collected in receiver 60, together with therelatively small quantity of cracked products of similar end-boilingpoint supplied to The topped crude and heavier condensed components ofthe vapors supplied to fractionator 39 from chamber 3| are supplied tofractionator 8, wherefrom the reflux condensate formed in this zone andthe heavy components of the topped crude are supplied to heating coil l.A cracking temperature of approximately 900 F. and a superatmosphericpressure of approximately 300 pounds per square inch are employed at theoutlet of heating coil I and this pressure is substantially equalized inreaction chamber 5 and fractionator 8. The distillate from receiver 60is utilized as absorber oil in absorber I and the enriched absorber oilfrom this zone is subjected to heating coil I I"! to a crackingtemperature of approximately 1000 F. at a superatmospheric pressure,measured at the outlet of the coil, of approximately 800 pounds persquare inch. Light reflux condensate from fractionator I6 is supplieddirectly to coil Ill.

An operation such as above outlined will produce, per barrel of chargingstock, approximately 58% of good quality gasoline, having an endboilingpoint of approximately 400 F. and an octane number of approximately 70by the motor method. Approximately 8%, based on the charging stock, ofrelatively low-boiling reflux condensate is recovered from fractionatorIt as a final product of the process. a gravity of approximately 32 A.P. I. and a boiling range of approximately 400 F. to 560 F. The otherproducts of the process are approximately 27% of residual liquid havinga gravity of about 8 A. P. I. and suitable for use as fuel oil, andapproximately 7% of light gases.

I claim as my invention:

1. In a process wherein a light hydrocarbon oil is cracked at crackingtemperature and superatmospheric pressure in a light oil cracking step,a heavier hydrocarbon oil cracked at cracking temperature andsuperatmospheric pressure in a heavy oil cracking step, resultant hotconversion products from both cracking steps separated into vaporous andliquid components at substantial superatmospheric pressure, saidvaporous components fractionated to form light and heavy refluxcondensates which are returned, respectively, to the light oil and heavyoil cracking steps, fractionated vapors of the desired end-boilingpoint, comprising gasoline and normally gaseous conversion products,subjected to condensation and the resulting distillate separated fromnormally gaseous products which include polymerizable olefins such aspropene and butenes, the improve- This product has ment which comprisesflash distilling said liquid components of the conversion products at asubstantially reduced pressure relative to that at which they areseparated from said vaporous components, fractionating the resultingevolved vapors out of contact with said vaporous components and incommingled state with uncracked hydrocarbon oil from an external source,recovering from the last mentioned fractionating step an overheaddistillate consisting of relatively low-boiling fractions of saiduncracked oil and relatively low-boiling fractions of the vapors evolvedby said flash distillation, contacting distillate thus recovered withsaid olefin-containing gases to absorb desirable high-boiling componentsof the latter, such as propene and butenes, and supplying the resultingenriched absorber oil to the light oil cracking step of the system fortreatment therein in commingled state with said light reflux condensate.

2. A process such as defined in claim 1 wherein condensate recoveredfrom the last mentioned fractionating step, which includes relativelyhighboiling fractions of the uncracked oil and relatively high-boilingfractions of the vapors evolved by said flash distillation, is suppliedfor cracking treatment to the heavy oil cracking step of the system.

3. A process such as defined in claim 1 wherein condensate resultingfrom the last mentioned fractionating step, which includes relativelyhigh-boiling components of the uncracked oil and relatively high-boilingcomponents of the vapors evolved by said flash distillation, is directlysupplied to the fractionating step of the system wherein said heavyreflux condensate is formed and fractionated therein in commingled statewith said vaporous components of the conversion products supplied tothis zone.

4. A process such as defined in claim 1 wherein condensate formed in thelast mentioned fractionating step and comprising components of theuncracked oil and the vapors evolved by said flash distillation whichboil above the range of said overhead distillate is further separatedinto light and heavy fractions which are returned, respectively, to thelight oil and heavy oil cracking step, said separation being efiected bycommingling said condensate with said vaporous components of theconversion products in the first mentioned fractionating step.

5. A process for the pyrolytic conversion of hydrocarbon oils whichcomprises heating an oil of relatively high-boiling characteristics tocracking temperature at superatmospheric pressure in a heating coil,heating an oil of lower boiling characteristics to an independentlycontrolled higher cracking temperature at superatmospheric pressure in aseparate heating coil, supplying resultant conversion products from bothheating coils to an enlarged reaction chamher also maintained atsubstantial superatmospheric pressure, separately removing vaporous andliquid conversion products from the reaction chamber, fractionating thevapors to form a heavy reflux condensate and a light reflux condensate,returning the heavy reflux condensate to the first mentioned heatingcoil for further cracking, returning the light reflux condensate to saidseparate heating coil for further cracking, subjecting resultantfractionated vapors of the desired end-boiling point to condensation,recovering as the resulting distillate cracked gasoline containingdissolved normally gaseous conversion products of the process,stabilizing the distillate to reduce its vapor pressure to the desireddegree by liberating therefrom regulated quantities of the dissolvednormally gaseous products, supplying gases liberated from the distillateby said stabilization to an absorber, contacting the same therein withan absorber oil derived as subsequently described and thereby absorbingdesirable high boiling components including propene and butenes from thegases, supplying the resulting enriched absorber oil to said separateheating coil, supplying said liquid conversion products removed fromsaid reaction chamber to a zone of substantially reduced pressure,therein appreciably vaporizing the same, recovering the resultingnon-vaporous residue, supplying the evolved vapors to a separatefractionating zone, contacting the same therein with a virgin oil ofrelatively wide boiling range and thereby fractionally distilling thelatter in commingled state with said evolved vapors, removingcondensate, comprising selected highboiling components of the virgin oiland of the evolved vapors, from the last mentioned fractionating zoneand supplying the same to the first mentioned fractionating zone,removing fractionated vapors of the desired end-boiling point,comprising selected low-boiling fractions of the virgin oil and of saidevolved vapors, from the last described fractionating step, subjectingthe same to condensation, and supplying resultant condensate as absorberoil to the absorber.

6. A conversion process which comprises subjecting hydrocarbon oilheavier than gasoline to cracking conditions of temperature and pressurein a heating coil and separating the same into vaporous and liquidconversion products in an enlarged chamber, removing the vaporousproducts and recovering therefrom a gasoline distillate and normallyincondensible gases formed by the cracking, separately removingunvaporized oil from the chamber and flash distilling the same bypressure reduction, fractionating resultant flashed vapors in contactwith crude petroleum, thereby vaporizing the low anti-knock gasolinefractions of the crude, condensing the uncondensed vapors from thefractionating step to form a condensate containing the low antiknockgasoline fractions of the crude, supplying to said heating coil liquidproducts of said fractionating step comprising portions of the crude andof the flashed vapors heavier than gasoline, scrubbing cracked normallyincondensible gases separated as aforesaid with at least a portion ofsaid condensate to absorb in the latter polymerizable olefiniccomponents of the gases, subjecting the thus enriched condensate toreforming conditions of temperature and pressure in a second heatingcoil and discharging the resultant products into said chamber.

.LYMAN C. HUFF.

